BLITS

{{Short description|Russian passive spherical reflector satellite}}

{{other uses}}

{{Infobox spaceflight

| name = BLITS

| image = BLITS 300c target.gif

| image_size = 220

| image_caption = An artist's impression of BLITS

| mission_type = Technology

| operator = Roskosmos
ILRS network

| website =

| COSPAR_ID = 2009-049G

| SATCAT = 35871

| mission_duration = Achieved: 3.5 years
Planned: 5 years

| spacecraft_bus =

| manufacturer = FSUE-IPIE

| launch_mass = {{convert|7.53|kg|lb}}

| dimensions =

| power =

| launch_date = {{start-date|17 September 2009, 15:55:07|timezone=yes}} UTC{{cite web|title=BLITS|url=http://ilrs.gsfc.nasa.gov/missions/satellite_missions/current_missions/blit_general.html|publisher=International Laser Ranging Service|access-date=2014-02-25|archive-url=https://web.archive.org/web/20131017012026/http://ilrs.gsfc.nasa.gov/missions/satellite_missions/current_missions/blit_general.html|archive-date=2013-10-17|url-status=dead}}

| launch_rocket = Soyuz-2-1b/Fregat

| launch_site = Baikonur Site 31/6

| launch_contractor =

| last_contact = March–April 2013

| decay_date =

| orbit_epoch = 25 February 2014, 08:51:29 UTC{{cite web|url=http://www.n2yo.com/satellite/?s=35871|title=BLITS Satellite details 2009-049G NORAD 35871|work=N2YO|date=25 February 2014|access-date=26 February 2014}}

| orbit_reference = Geocentric

| orbit_regime = Low Earth

| orbit_periapsis = {{convert|823|km|mi}}

| orbit_apoapsis = {{convert|829|km|mi}}

| orbit_inclination = 98.55 degrees

| orbit_semimajor = {{convert|7197.67|km|mi}}

| orbit_eccentricity = 0.0004373

| orbit_period = 101.28 minutes

| orbit_RAAN = 105.39 degrees

| orbit_arg_periapsis = 71.58 degrees

| apsis = gee

}}

BLITS (Ball Lens In The Space) is a Russian satellite launched on September 17, 2009, as a secondary payload on a Soyuz-2.1b/Fregat, from the Baikonur Cosmodrome in Kazakhstan.

The satellite is totally passive and spherical, and is tracked using satellite laser ranging (SLR) by the International Laser Ranging Service.{{cite journal |last1=Pearlman |first1=M. |last2=Arnold |first2=D. |last3=Davis |first3=M. |last4=Barlier |first4=F. |last5=Biancale |first5=R. |last6=Vasiliev |first6=V. |last7=Ciufolini |first7=I. |last8=Paolozzi |first8=A. |last9=Pavlis |first9=E. C. |last10=Sośnica |first10=K. |last11=Bloßfeld |first11=M. |title=Laser geodetic satellites: a high-accuracy scientific tool |journal=Journal of Geodesy |date=November 2019 |volume=93 |issue=11 |pages=2181–2194 |doi=10.1007/s00190-019-01228-y|bibcode=2019JGeod..93.2181P |s2cid=127408940 }} The design of BLITS is based on the optical Luneburg lens concept. The retroreflector is a multilayer glass sphere; it provides uniform reflection characteristics when viewed within a very wide range of angles, and can provide a cross-section sufficient for observations at low to medium orbit heights. A similar design was already tested on a smaller laser reflector carried on board of the METEOR-3M spacecraft launched on December 10, 2001.{{cite web|title=Spherical Retroreflector with an Extremely Small Target Error: International Experiment in Space

|url=http://cddis.nasa.gov/lw13/docs/papers/target_vasiliev_1m.pdf

|work=13th International Workshop on Laser Ranging. Toward Millimeter Accuracy|publisher=NASA}}

The purpose of the mission was to validate the spherical glass retroreflector satellite concept and obtain SLR (Satellite Laser Ranging) data for solution of scientific problems in geophysics, geodynamics, and relativity. The BLITS allows millimeter and submillimeter accuracy SLR measurements, as its "target error" (uncertainty of reflection center relative to its center of mass) is less than 0.1 mm. An additional advantage is that the Earth's magnetic field does not affect the satellite orbit and spin parameters, unlike retroreflectors incorporated into active satellites. The BLITS allows the most accurate measurements of any SLR satellites, with the same accuracy level as a ground target.{{cite web| url=http://cddis.gsfc.nasa.gov/lw17/docs/presentations/session6/07-kasi_blits.pdf

|title=BLITS: spin parameters and its optical response measured by the Graz 2kHz SLR system}}

The satellite was inserted into an {{cvt|832|km|||}} Sun-synchronous orbit, with an inclination of 98.85º.{{cite journal |last1=Sośnica |first1=Krzysztof |last2=Jäggi |first2=Adrian |last3=Meyer |first3=Ulrich |last4=Thaller |first4=Daniela |last5=Beutler |first5=Gerhard |last6=Arnold |first6=Daniel |last7=Dach |first7=Rolf |title=Time variable Earth's gravity field from SLR satellites |journal=Journal of Geodesy |date=October 2015 |volume=89 |issue=10 |pages=945–960 |doi=10.1007/s00190-015-0825-1|bibcode=2015JGeod..89..945S |doi-access=free }} The satellite was spinning at a spin period of 5.6 seconds around the axis normal to its orbit plane, allowing laser light to be reflected in short bursts because only half of the satellite is covered in a reflective coating. As the satellite is made of glass, minimal in-flight spin slowdown was expected since there were no conducting parts where currents interacting with the Earth magnetic field can be induced.

The expected operative life was at least five years, but the mission was interrupted in 2013 after a collision with space debris.{{cite web |title=Russian BLITS Satellite hit by Space Debris |url=http://www.spaceflight101.net/blits-satellite-collision-january-2013.html |website=Spaceflight101: Space News and Beyond |access-date=16 April 2020 |archive-url=https://archive.today/20161005043844/http://www.spaceflight101.net/blits-satellite-collision-january-2013.html |archive-date=2016-10-05 |date=9 March 2013 |url-status=usurped}}{{cbignore|bot=InternetArchiveBot}}